The subject matter described and/or illustrated herein relates generally to electrical contacts, and more particularly, to an assembly of mated electrical contacts.
Complementary electrical contacts are configured to mate together at a contact interface where mating elements of the complementary electrical contacts engage (i.e., physically contact) each other. Many electrical contact assemblies form a Hertzian style contact interface when the mating elements of the complementary electrical contacts engage each other. Hertzian contact interfaces are formed when the mating element of one of the complementary electrical contacts includes a curved surface that engages a curved or approximately flat surface of the mating element of the other complementary electrical contact. The curved surface(s) deforms slightly under the contact force that holds the mating elements in engagement. For example, a Hertzian style contact interface is formed when a mating element in the form of a spherical protrusion engages an approximately flat (i.e., planar) surface of the mating element of the complementary electrical contact.
Hertzian contact interfaces are not without disadvantages. For example, the mechanical and electrical distributions across the Hertzian contact interface are typically not coincident. Specifically, the regions within the Hertzian contact interface having the greatest mechanical contact pressure (i.e., the greatest normal load or the greatest normal pressure) have different locations within the Hertzian contact interface than the regions within the Hertzian contact interface that carry the greatest amount of electrical current (i.e., the greatest current density). For example, the maximum mechanical contact pressure may be located at the center of the Hertzian contact interface, while the maximum amount of electrical current is distributed across the outer perimeter of the Hertzian contact interface. As a result of the mechanical and electrical distributions not being coincident, only a portion (e.g., a minority) of the area of the Hertzian contact interface is contributing to the flow of electrical current, which may lead to greater overall contact resistance and/or a greater localized thermal response.
Moreover, in situations wherein a shear force is applied to the Hertzian contact interface (e.g., from vibrational and/or thermal effects), mechanical degradation of the Hertzian contact interface will first occur where the lateral deformation is the greatest but the mechanical contact pressure is the lowest. In other words, shear forces may cause the Hertzian contact interface to mechanically degrade (e.g., break, fracture, wear, and/or the like) first at the regions that carry the greatest amount of electrical current, which may reduce the amount of electrical current that is carried by the Hertzian contact interface to fall below desired levels and/or may cause the electrical contacts to completely lose electrical contact therebetween. Shear forces may be especially problematic for Hertzian contact interfaces that are formed from electrical contacts that include non-noble metal coatings (e.g., Sn), which may require a higher normal load to penetrate the inherent oxide film that forms on non-noble metal coatings.